Lately, an information processing system based on peer-to-peer (P2P) has been used. In P2P information processing system, each peer (node) stores information and also registers information in another node or requests another node to register information. In this information processing system, a certain node receives and stores information (hereinafter called “data”) output from a mobile device, for example. Then, in response to a query concerning a certain item of data from a center server, a node storing this item of data sends it to the center server.
In this information processing system, items of data concerning plural devices are distributed over plural nodes and are stored in them, based on the distributed hash table (DHT) method. According to the DHT method, a node that stores an item of data (hereinafter called “register node”) is determined based on a hash function, for example.
A node that receives data from a device sends the data to a register node directly or via at least one node. A relay node transfers the received data to the register node, and the register node stores the received data. If data register processing is performed highly frequently, data transfer processing is also performed highly frequently, thereby increasing a network load.
Accumulating items of data for a predetermined period of time before transferring data and then sending the accumulated items of data together at one time has been proposed. Such integrated data sending reduces the network load. Technologies concerning the network efficiency are discussed in, for example, Japanese National Publication of International Patent Application No. 2015-524586, Japanese Laid-open Patent Publication Nos. 2014-103553 and 2006-203537, and Apache Kafka, 4.4 The Producer.